People Are Still Getting the Plague. Here's What You Need to Know

Two counties in Arizona have confirmed that fleas in the area have tested positive for the plague. The infected fleas were initially found on prairie dogs in Coconino County, and health experts have confirmed there are fleas carrying the disease in Navajo County as well. So far, no cases of plague have been found among people in Arizona, but the news comes just a months after three cases of plague in humans were confirmed in New Mexico.

Should you be worried? TIME breaks down what you need to know about bubonic plague in the U.S.

What is the plague?

Plague is an infectious disease that is caused by the Yersinia pestis bacteria. It largely affects rodents, but other animals and humans can be infected as well. People can get the plague if they are bitten by an infected flea or if they come in contact with tissues or fluids of an animal that has the disease. There are three different types of plague: bubonic, septicemic and pneumonic. More than 80% of plague cases in the U.S. are bubonic, which causes fever, headache, chills and weakness. There is a chance that people can become infected from close contact with humans who have the pneumonic plague, but it’s not common.

What happened in Arizona and New Mexico?

Health officials in the two Arizona counties have found that local fleas are carrying the disease. The counties are warning people to reduce their risk for potential exposure by taking precautions like avoiding sick or dead animals, preventing pets from running loose.

The New Mexico Department of Health reported in June that it had identified plague in three people. The first case was in a 63-year-old man. Health experts also identified plague in two women, one age 52 and another age 62, from Santa Fe County, bringing the total number of plague cases in the state to three so far in 2017, though no one has died. All three people needed to be hospitalized. No further information has been provided about how the women contracted the disease.

Is the plague common?

No. In the United States there are an average of seven human plague cases reported each year. Between 1900, when plague first appeared in the U.S., and 2012, the U.S. Centers for Disease Control and Prevention (CDC) reports that there have been 1,006 cases of confirmed or probable plague cases in the U.S. There have been outbreaks of the disease worldwide, and about 1,000 to 2,000 cases are reported globally each year.

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What are the symptoms of the plague?

People who get the bubonic plague may experience fever, chills and weakness as well as painful lymph nodes. Septicemic plague has similar symptoms, as well as possible shock and bleeding in the skin and organs. Some of a person’s tissue on their toes, fingers and nose could turn black and die. The last type of plague, pneumonic, is also characterized by fever and chills, as well as respiratory problems like chest pain, cough and shortness of breath. It’s considered the most severe form of the disease.

Is it deadly?

The death rate from plague is about 11%, thanks to the availability of antibiotics that can treat it. The CDC says the risk of death from the bubonic plague is likely even lower than that of the other strains. In the past, when there were no antibiotics to treat the plague, the mortality rate was estimated to be more than 65%. Left untreated, the disease can still be serious.

How can I protect myself?

For people who want to lower their already-low risk, experts recommend reducing the likelihood that rodents are around your home by getting rid of junk, cluttered firewood or brush or pet food outside. If a person needs to handle a potentially infected animal, the CDC recommends they use gloves and call their local health department about how to dispose of a dead animal. During camping or hiking, people should use bug repellent. Lastly, pets can pick up the disease, which is why people should use pest control products and seek medical help right away if a pet seems ill.

“Pets that are allowed to roam and hunt can bring infected fleas from dead rodents back into the home, putting you and your children at risk,” said Dr. Paul Ettestad, a public health veterinarian for the New Mexico Department of Health in a statement. “Keeping your pets at home or on a leash and using an appropriate flea control product is important to protect you and your family.”